1. Field of the Invention
The present invention relates to an antenna for transmitting or receiving radio waves.
2. Related Background Art
A variety of antennas with a conductor pattern as an antenna element on a base are known. For example, Japanese Patent Application Laid Open No. 2000-82914 discloses a microstrip antenna having a base made of a magnetic material, and Japanese Patent Application Laid Open No. H9-121114 discloses a microstrip antenna having a base made of a dielectric material. Further, Japanese Patent Applications Laid Open Nos. 2004-363859 and 2002-374122 disclose antennas having a base made of a dielectric material or magnetic material.
It is an important object to reduce the physical dimension of antennas to be set in small devices while keeping a wide operating frequency bandwidth for the antennas. In order to obtain a small antenna, it is effective to insert a reactance element in the antenna element. However, in this case, there is a problem that the operating frequency bandwidth is narrow.